Permutation lock



April 1939- G. D. DILLON 2,152,839

f \PERMUTATION LOCK Filed Sept. 50, 1938 fed/ye .19. Ji/Zwz.

Patented Apr. 4, 1939 UNITED s'rg'rss PATENT orriel:

Claims.

This invention relates to improvements in permutation locks and relatesmore particularly to an attachment that can be applied to such locks topreventthem from being opened by a 5 removal of the tumblers.

It often happens that safes in small stores, banks and other places areopened by burglars and the cash or other valuables taken. The ordinarycheap safes are almost without exception provided with combination orpermutation locks of the type in which a plurality of circular disks ortumblers are positioned in a box on the inside of the door andmanipulated by a knob that is located on the outside of the door. Eachtumbler has a notch in its periphery and a gravity dog rests on theperipheries of the tumblers and normally holds the bolts in projected orlooking position. When the tumblers have been adjusted so as to bringthe notches in line underneath the gravity dog, the latter will drop andrelease the bolts which can then be withdrawn.

Most burglars, whatever method they use, first break the outside knobfrom the safe so as to furnish access to the interior of the lock box.After the knob has been removed the tumblers are then driven inwardly bymeans of a punch and sledge, or by means of an explosive. The idea beingto remove the tumblers so that the gravity dog will drop and release thebolts, which can then be withdrawn in the usual way.

It is the object of this invention to provide means, within the lockbox, for automatically engaging the gravity dog and latching it in boltengaging position, whenever the tumblers are subjected to abnormalmovement or to severe shocks, as when the knob is being forcibly brokenaway.

In order to describe the invention so that it can be readily understood,reference will now be had to the accompanying drawing in which it hasbeen illustrated and in which Figure 1 is a side elevation of acombination lock, showing the tumblers and the safety attachment inplace, the gravity dog having been omitted for the sake of clearness.

Figure 2 is an end elevation, looking in the direction of arrow 2 inFig. 1, the gravity dog being shown in position.

Figure 3 is a section taken on line 33, Fig. 2 and shows the latch thatholds the safety device inoperative.

Figure 4 is asection taken on line 4-4, Fig. 1 and shows the dogengaging member, and

Figure5 shows a proposed modification.

In the drawing numeral 6 designates the door of the safe and I the lockbox which is attached to the inside of the door. Numerals S designatethe tumblers and 9 the knob that is positioned on the outside of thedoor and which is operatively connected with the tumblers by means of ashaft Ill. The construction of the lock has not been shown because it isold and well known. The tumbler farthest to the left in Fig. l isattached directly to shaft It and serves to set the other tumblers whichbecome temporarily interconnected when pins ll come into engagement.Each tumbler is provided with one peripheral notch I2 and when these arebrought into alignment directly below the elongated pawl I3 of thegravity dog I 4 the pawl drops into the notches and its movement aboutthe pivot I 5 releases the bolts which can then be withdrawn.

It is evident that if the tumblers are removed from beneath the pawl ISthe dog can turn and release the look. If after the knob has been brokenoff a punch is applied to the outer end of the shaft I0 and the latteris driven inwardly carrying with it the tumblers so that they areremoved, the gravity dog is free to turn and release the bolt.

It is evident from the above that as long as the gravity dog remains inthe position shown in Fig, 2 the lock cannot be opened even if thetumblers are removed.

For the purpose of automatically moving a support into place under theprojection I6 of dog M, whenever the tumblers are subjected to a forcewhich moves them inwardly the following mechanism has been provided.

A square bar I! is provided at each end with an attaching membercomprising a rectangular portion [8 from diagonal corners of whichprojections I9 extend. The projections are perforated for the receptionof screws 2!) by means of which the assembly is attached to a corner ofthe lock box I in the manner shown in Fig. 2. Slidably mounted on thebar, between the two end supports are two square rings 2| and 22. Theone to the right in Fig. 1 is provided with a set screw 23 by means ofwhich it can be clamped in any suitable position. Member 2i is providedon one side with an integral arm 26 having a narrow flange along itslower edge. A compression spring 25 surrounds the bar I! between partsI8 and 2| and tends to move member 2| towards member 22 that serves as astop. The end support l8 at the left in 'Fig. 1 is provided at its innercorner with two lugs or ears 26 between which is pivoted a bell cranklever having arms 21 and 28. It will be observed that the slidable loop2| is provided with a lug 29 and that the end of arm 28 has a hook 30that engages lug 29 and latches member 2! against movement in responseto the action of spring 25. Attached to am 2'5 is an extension Bl whichhas a slot 32 for the reception of the clamping bolt 33. The outer endof the extension 3! has a head 34 that rests against the outer surfaceof the innermost tumbler or disk 8. Stop 22 is so positioned that whenmember H is released and moved against this stop by the action of thespring, the end of the slidable extension 35 of arm 24 will bepositioned underneath lug E6 of the gravity dog It and support the;latter so that it will not move downwardly if the tumblers 8 areremoved. In order to prevent member 2! from being moved away from thestop 22 after it has been released, a hook 36 may be 'pivotally attachedto member 22 and so proportioned that it will engage arm 2 and latch theparts in the position shown in Fig. 5. A lug 3'! serves to limit thedownward movement of hook 36 and a spring 38 holds the hook normally inengagement with lug 37.

Let us now assume that the parts are in the position shown in Fig. 1 andthat an attempt is made to open the safe. The burglar, by means of achisel and sledge, removes the knob 9, as by breaking shaft II). He thenbegins to drive shaft I 0 inwardly by means of a punch and sledge andsince the innermost disk 8 is attached to the shaft Iii it will be movedinwardly. The inward movement of disk 8 turns the bell crank lever aboutits pivot and disengages hook 30 from lug 29 and thereby releases slide2|, which isimmediately moved towards stop 22 by the action of thespring 25. This movement of slide 2| brings the end of arm 35 underneathlug IS in the manner indicated in Fig. 2 and supports the gravity dog insuch a way that it will not move to unlocking position even after all ofthe disks 8 have been removed. The burglar then finds that the lock willnot open and unless he is familiar with the construction of the safetycatch and provided with special tools, he will be unable to open thelook after having removed the tumblers.

The attachment is of simple construction and can be readily applied toany lock or may be supplied as standard equipment when the lock ismanufactured. By making arms 24 and 21 in two parts the device can beadjusted to fit all sizes of locks.

In the drawing bar 11 has been shown as square but it may have any othernon-circular cross section and may also be round, but in the latter casethe slidable ring 2! must have a splined connection that prevents itfrom rotating on the shaft.

If the gravity dog is not provided with a lug I 6 such a lug may bewelded thereto when the safety attachment is installed.

Having thus described the invention, what is claimed as new is:

1. In a permutation lock having a plurality of spaced parallel tumblersmounted for coaxial rotation, each tumbler having a peripheral notch,and a gravity dog having a pawl portion, supported on the peripheries ofthe tumblers, means for engaging and supporting the dog independently ofthe tumblers comprising a guide, a slide movable thereon, meanscomprising a spring for urging the slide in one direction, a latch forholding the slide from movement, a supporting arm carried by the slidefor engaging thedog and supporting it when the slide is in apredetermined position and means operated by an abnormal movement of thetumbler for releasing the latch, thereby permitting the slide to move inresponse to the action of the spring and bring the supporting arm intodog engaging position.

2. In a permutation lock having a plurality of spaced parallel tumblersmounted for coaxial rotation, each tumbler having a peripheral notch,and a gravity dog having a pawl portion, supported on the peripheries ofthe tumbler, means for engaging and supporting the dog independently ofthe tumblers comprising a guide, a slide movable thereon, meanscomprising a spring for urging the slide in one direction, a latch forholding the slide from movement, a supporting arm carried by. the slidefor engaging the dog and supporting it when the slide is in apredetermined position, a stop adjustably attached to the guide, andmeans operated by an abnormal movement of the tumblers for releasing thelatch, thereby permitting the slide to move in response to the action ofthe spring and bring the supporting arm into dog engaging position.

3. A safety device for use in a permutation lock having a plurality ofaxially aligned rotatable tumblers having each a peripheral notch, and alock releasing gravity dog normally held in operative position by thetumblers, means for engaging and holding the dog in operative positionindependently of the tumblers comprising a guide, means for holding theguide in a predetermined position relative to the tumblers and dog, aslide non-rotatably but longitudinally movable on the guide, an armprojecting from the slide, positioned to engage and support the gravitydog when the slide is in a predetermined position, means comprising aspring for urging the slide to dog engaging position, a stop on theguide for limiting the movement of the slide in response to the actionof the spring, a latch for holding the slide in opposition to the actionof the spring, and means operated by the movement of a tumbler in thedirection of its axis of rotation for releasing the latch.

4. A permutation lock comprising in combination, a plurality oflongitudinally spaced coaxial tumblers having each a peripheral notch, abolt latching gravity dog having a pawl positioned for movement into thenotches when they are positioned in alignment, a dog supporting arm,mounted for movement to and from dog engaging position, resilient meansfor urging the arm into engagement with the dog to stop its movementtowards bolt releasing position, a latch for holding the arm against theaction of the spring, and means responsive to an abnormal movement ofthe tumblers for releasing the latch whereby the arm may move tooperative position.

5. A safety attachment for use in a permutation lock having a pluralityof tumblers and, a bolt latching dog held in operative position by thetumblers, comprising in combination, two spaced brackets, a noncircularguide having one bracket attached to each end, a slide carried on theguide, a pawl engaging arm extending laterally from the guide, a springencircling the guide between one bracket and the slide, a triggerpivoted to the bracket which serves as an abutment for the spring, theslide and the trigger having cooperating latching means for holding theslide in a predetermined position in opposition to the action of thespring, and an angular extension of the trigger for engagement with thetumblers of a permutation lock.

GEORGE D. DILLON

